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Isotopes of selenium



Selenium (Se) has six naturally-occurring isotopes, five of which are stable: 74Se, 76Se, 77Se, 78Se, and 80Se. The last three also occur as fission products, along with 79Se which has a halflife of 295,000 years, and 82Se which has a very long half life (~1020 yr, decaying via double beta decay to 82Kr) and for practical purposes can be considered to be stable. 23 other unstable isotopes have been characterized.
Standard atomic mass: 78.96(3) u

Additional recommended knowledge

Table

nuclide
symbol
Z(p) N(n)  
isotopic mass (u)
 
half-life nuclear
spin
representative
isotopic
composition
(mole fraction)
range of natural
variation
(mole fraction)
excitation energy
65Se 34 31 64.96466(64)# <50 ms 3/2-#
66Se 34 32 65.95521(32)# 33(12) ms 0+
67Se 34 33 66.95009(21)# 133(11) ms 5/2-#
68Se 34 34 67.94180(4) 35.5(7) s 0+
69Se 34 35 68.93956(4) 27.4(2) s (1/2-)
69m1Se 39.4(1) keV 2.0(2) µs 5/2-
69m2Se 573.9(10) keV 955(16) ns 9/2+
70Se 34 36 69.93339(7) 41.1(3) min 0+
71Se 34 37 70.93224(3) 4.74(5) min 5/2-
71m1Se 48.79(5) keV 5.6(7) µs 1/2- to 9/2-
71m2Se 260.48(10) keV 19.0(5) µs (9/2)+
72Se 34 38 71.927112(13) 8.40(8) d 0+
73Se 34 39 72.926765(11) 7.15(8) h 9/2+
73mSe 25.71(4) keV 39.8(13) min 3/2-
74Se 34 40 73.9224764(18) STABLE 0+ 0.0089(4)
75Se 34 41 74.9225234(18) 119.779(4) d 5/2+
76Se 34 42 75.9192136(18) STABLE 0+ 0.0937(29)
77Se 34 43 76.9199140(18) STABLE 1/2- 0.0763(16)
77mSe 161.9223(7) keV 17.36(5) s 7/2+
78Se 34 44 77.9173091(18) STABLE 0+ 0.2377(28)
79Se 34 45 78.9184991(18) 2.95(38)E+5 a 7/2+
79mSe 95.77(3) keV 3.92(1) min 1/2-
80Se 34 46 79.9165213(21) STABLE 0+ 0.4961(41)
81Se 34 47 80.9179925(22) 18.45(12) min 1/2-
81mSe 102.99(6) keV 57.28(2) min 7/2+
82Se 34 48 81.9166994(22) 97(5)E+18 a 0+ 0.0873(22)
83Se 34 49 82.919118(4) 22.3(3) min 9/2+
83mSe 228.50(20) keV 70.1(4) s 1/2-
84Se 34 50 83.918462(16) 3.1(1) min 0+
85Se 34 51 84.92225(3) 31.7(9) s (5/2+)#
86Se 34 52 85.924272(17) 15.3(9) s 0+
87Se 34 53 86.92852(4) 5.50(12) s (5/2+)#
88Se 34 54 87.93142(5) 1.53(6) s 0+
89Se 34 55 88.93645(32)# 0.41(4) s (5/2+)#
90Se 34 56 89.93996(43)# 300# ms [>300 ns] 0+
91Se 34 57 90.94596(54)# 270(50) ms 1/2+#
92Se 34 58 91.94992(64)# 100# ms [>300 ns] 0+
93Se 34 59 92.95629(86)# 50# ms [>300 ns] 1/2+#
94Se 34 60 93.96049(86)# 20# ms [>300 ns] 0+

Notes

  • The precision of the isotope abundances and atomic mass is limited through variations. The given ranges should be applicable to any normal terrestrial material.
  • Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses.
  • Uncertainties are given in concise form in parentheses after the corresponding last digits. Uncertainty values denote one standard deviation, except isotopic composition and standard atomic mass from IUPAC which use expanded uncertainties.

References

  • Isotope masses from Ame2003 Atomic Mass Evaluation by G. Audi, A.H. Wapstra, C. Thibault, J. Blachot and O. Bersillon in Nuclear Physics A729 (2003).
  • Isotopic compositions and standard atomic masses from Atomic weights of the elements. Review 2000 (IUPAC Technical Report). Pure Appl. Chem. Vol. 75, No. 6, pp. 683-800, (2003) and Atomic Weights Revised (2005).
  • Half-life, spin, and isomer data selected from these sources. Editing notes on this article's talk page.
    • Audi, Bersillon, Blachot, Wapstra. The Nubase2003 evaluation of nuclear and decay properties, Nuc. Phys. A 729, pp. 3-128 (2003).
    • National Nuclear Data Center, Brookhaven National Laboratory. Information extracted from the NuDat 2.1 database (retrieved Sept. 2005).
    • David R. Lide (ed.), Norman E. Holden in CRC Handbook of Chemistry and Physics, 85th Edition, online version. CRC Press. Boca Raton, Florida (2005). Section 11, Table of the Isotopes.


Isotopes of arsenic Isotopes of selenium Isotopes of bromine
Index to isotope pages
 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Isotopes_of_selenium". A list of authors is available in Wikipedia.
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